diff --git a/lib/error.js b/lib/error.js
deleted file mode 100644
index 298fc6d..0000000
--- a/lib/error.js
+++ /dev/null
@@ -1,31 +0,0 @@
-const PlugableError = class PlugableError extends Error {
-  constructor(code, message, ...contexts) {
-    if (Array.isArray(message)) {
-      message = message.filter(function (line) {
-        return !!line;
-      }).join(' ');
-    }
-    message = `${code}: ${message}`;
-    super(message);
-    if (Error.captureStackTrace) {
-      Error.captureStackTrace(this, PlugableError);
-    }
-    this.code = code;
-    for (const i = 0; i < contexts.length; i++) {
-      const context = contexts[i];
-      for (const key in context) {
-        if (key === 'code') {
-          continue;
-        }
-        const value = context[key];
-        if (value === void 0) {
-          continue;
-        }
-        this[key] = Buffer.isBuffer(value) ? value.toString() : value === null ? value : JSON.parse(JSON.stringify(value));
-      }
-    }
-  }
-};
-export default (function () {
-  return new PlugableError(...arguments);
-});
diff --git a/lib/error.ts b/lib/error.ts
new file mode 100644
index 0000000..c091567
--- /dev/null
+++ b/lib/error.ts
@@ -0,0 +1,45 @@
+const PlugableError = class PlugableError extends Error {
+  private code: string;
+  [index: string]: unknown; // required to allow adding class props dynamically
+  constructor(
+    code: string,
+    message: string | (string | undefined)[],
+    ...contexts: Record<string, object>[]
+  ) {
+    if (Array.isArray(message)) {
+      message = message
+        .filter(function (line) {
+          return !!line;
+        })
+        .join(" ");
+    }
+    message = `${code}: ${message}`;
+    super(message);
+    if (Error.captureStackTrace) {
+      Error.captureStackTrace(this, PlugableError);
+    }
+    this.code = code;
+    for (let i = 0; i < contexts.length; i++) {
+      const context = contexts[i];
+      for (const key in context) {
+        if (key === "code") {
+          continue;
+        }
+        const value = context[key];
+        if (value === void 0) {
+          continue;
+        }
+        this[key] = Buffer.isBuffer(value)
+          ? value.toString()
+          : value === null
+            ? value
+            : JSON.parse(JSON.stringify(value));
+      }
+    }
+  }
+};
+export default (function (
+  ...args: ConstructorParameters<typeof PlugableError>
+) {
+  return new PlugableError(...args);
+});